Aircraft landing gear with highly offset strut pivot axis

ABSTRACT

The invention relates to aircraft landing gear of the type comprising a leg ( 11 ) constituted by a strut ( 12 ) receiving a telescopic rod ( 13 ) to slide on a sliding axis (Z), said strut being hinged to an aircraft structure and being capable of pivoting about a pivot axis (X) that is highly offset from the sliding axis (Z). In accordance with the invention, the landing gear ( 10 ) includes a connection structure ( 100 ) essentially constituted by two panels ( 101, 102 ) connecting two axially separate points of the strut ( 12 ) to a common axis structure ( 103 ) extending along the strut pivot axis (X). In the gear-down position, the panels ( 101, 102 ) are one above the other, the top panel ( 101 ) being connected to the strut ( 12 ) via a high attachment ( 105 ) which is rigid in twisting, while the bottom panel ( 102 ) is connected to the strut ( 12 ) via a low attachment ( 106 ) which tolerates twisting, thereby enabling the strut ( 12 ) to warp to some extent when the aircraft is turning while taxiing.

[0001] The present invention relates to an aircraft undercarriage of thetype comprising a leg constituted by a strut in which there slides atelescopic rod that forms a shock absorber, the free end of the rodbeing hinged to a rocker beam carrying a multiple-axle wheel set.

[0002] The invention relates more particularly to landing gear in whichthe leg strut is hinged so as to be capable of being pivoted by anassociated connection structure about a substantially horizontal axisthat is highly offset from the sliding axis of the telescopic rod whichis vertical in the gear-down position.

[0003] It has been known for a long time to make landing gear structuresin which the pivot axis is not coplanar with the sliding axis of thetelescopic rod. Nevertheless, in existing embodiments, the offset isgenerally relatively small, which has always-made it possible toenvisage making a one-piece strut combining both the cylinder portion inwhich the telescopic rod slides and the lugs that receive the bearingsfor hinging the landing gear to the aircraft, said bearings defining thepivot axis of the leg, with this being achievable under conditions thatare technologically and economically acceptable.

[0004] Such structures are illustrated, for example, in document DE-A-2924741. That document describes a fuselage undercarriage of the type thatis raised laterally, in which the strut is hinged to the fuselage abouta horizontal axis extending longitudinally and that is offset from thesliding axis of the telescopic rod.

[0005] The provision of aircraft of ever-increasing weight has led tolanding gear being devised comprising a large number of wheels and/or aplurality of undercarriages fitted with wheel sets. One of theretracting mechanisms envisaged for that kind of landing gear thenrequires structures in which the pivot axis is highly offset relative tothe sliding axis of the telescopic rod, in which case it becomestechnologically or economically inconceivable to make the strut as asingle piece.

[0006] This leads to providing an associated connection structure thatprovides a mechanical connection between the strut proper and thebearings defining the pivot axis of said strut.

[0007] Proposals have already been made to make such a connectionstructure in integral form or in the form of an assembly of a pluralityof bars. Such a configuration is unsuitable for landing gear where therocker beam carries a large number of wheels because of the inability ofthe structure to transmit effectively the large twisting moment-that isgenerated while the aircraft is taxiing, and in particular while it isturning.

[0008] A bar structure is thus illustrated in document U.S. Pat. No.1,914,092, which describes tail landing gear presenting a hinged axisconnecting it to the fuselage, which axis is highly offset relative tothe pivot axis of the tail wheel. Pivoting of the tail wheel prevents itfrom transmitting twisting torque to the structure, so a barconfiguration is entirely suitable. This would not apply if saidstructure were to be subjected to twisting.

[0009] In a variant, proposals have been made to implement theabove-mentioned connection structure in the form of lateral panels eachextending in a plane that is vertical when in the gear-down position,the two planes intersecting on the sliding axis of the telescopic rod.That structure is likewise unsuitable for landing gear in which therocker beam carries a large number of wheels since it is incapable oftransmitting high twisting moments effectively as generated when theaircraft is turning while taxiing.

[0010] One such structure is illustrated by document GB-A-1 490 088which relates to landing gear having a complex mechanism in which thestrut possesses a hinge axis that is offset relative to the sliding axisof the telescopic rod. To connect the hinge bearings to the cylinder ofthe strut, the strut is provided with two lateral panels extending inrespective planes that are vertical in the gear-down panels with theaxis of intersection between the planes coinciding with the slidingaxis. To make this structure suitable for withstanding stresses comingfrom the ground, the lateral panels are provided with thick margins inorder to prevent the panels from flexing. That disposition is heavy andill-adapted to large undercarriages of the type presently underconsideration.

[0011] The invention seeks to devise a novel landing gear structure thatis specially adapted to undercarriages presenting a pivot axis that issubstantially horizontal and highly offset relative to the sliding axisof the telescopic rod, which axis is substantially vertical in thegear-down position.

[0012] An object of the invention is thus to provide landing gearincluding a connection structure suitable for transmitting effectivelythe twisting moments that are generated while the aircraft is taxiing,in particular while it is turning.

[0013] In accordance with the invention, this problem is solved byaircraft landing gear of the type comprising a leg constituted by astrut in which a telescopic shock-absorber rod slides along a slidingaxis, the free end of the rod being hinged to a rocker beam carrying awheel set having multiple axles, said strut being hinged to a structureof the aircraft and being capable of being pivoted by an associatedconnection structure about a substantially horizontal axis that ishighly offset from the sliding axis of the telescopic rod which isvertical in the gear-down position. According to the invention, theconnection structure is essentially constituted by two panels connectingtwo axially separate points of the strut to a common axis structureextending along the pivot axis of said strut, in such a manner that inthe gear-down position said panels are disposed one above the other,with a top panel which is connected to the strut via a high attachmentwhich is rigid in twisting, and with a bottom-panel which is connectedto the strut via a low attachment which tolerates twisting, therebyallowing the strut to warp to some extent when the aircraft is turningwhile taxiing.

[0014] Because of the above-specified attachments, the ability of thelow attachment between the bottom panel and the strut to toleratetwisting enables the strut to be warped to some extent when the aircraftis turning while taxiing without that harming the stability of the leg,given that the structure of the high attachment is rigid in twisting.

[0015] Preferably, the top panel and the bottom panel both extend inrespective planes each containing the pivot axis of the strut, the planeof the top panel being substantially orthogonal to the sliding axis ofthe telescopic rod.

[0016] Advantageously, the top and bottom panels are constituted byplane pieces with stiffened margins.

[0017] The high attachment between the top panel and the strut, whichattachment is rigid in twisting, may be implemented in various ways, andspecific mention may be made of a restrained connection or a connectionwhich is totally rigid by being welded to or being formed integrallywith said strut, or indeed a hinged connection about an axis containedin the plane of the panel and extending parallel to the pivot axis ofsaid strut.

[0018] The low attachment between the bottom panel and the strut iscapable of tolerating twisting and may likewise be made in various ways:for example it may be a connection hinged about an axis contained in theplane of the bottom panel and parallel to the pivot axis of said strut,or a swivel connection associated with a stub axle projecting from thestrut, or indeed a restrained connection to at least one lug projectingfrom said strut.

[0019] In general, it is advantageous to provide for the high and lowattachments to be level with sliding bearing surfaces for the telescopicrod inside the strut when the rod is in its pushed-in positioncorresponding to supporting the aircraft on the ground. Thus, while theaircraft is taxiing, loads generated normal to the axis of the strut andpassing via said bearing surfaces are countered directly by the top andbottom panels, thus avoiding undesirable bending of the strut.

[0020] The common axis structure can be a separate part including thepivot bearings for pivoting the strut about its pivot axis, saidseparate part being fixed to the top and bottom panels via lugs that aresecured to the part and/or to said panels.

[0021] In a variant, the common axis structure is integral with one ofthe panels.

[0022] In another variant, the common axis structure includes a panelportion that is fixed to the top panel and/or to the bottom panel, saidpanel portion being coplanar with and extending the associated panel.

[0023] Other characteristics and advantages of the invention appear moreclearly in the light of the following description and the accompanyingdrawings, relating to particular embodiments and given with reference tothe figures, in which:

[0024]FIG. 1 is a perspective view of an aircraft landing gear fitted inaccordance with the invention with a connection structure constituted bytwo panels which are superposed in the gear-down position, beingconnected to a common axis structure extending along the pivot axis ofthe strut, said panels being symbolized by shaded triangles;

[0025]FIG. 2 is an elevation view of a strut fitted with a connectionstructure having two superposed panels, showing a first embodiment ofthe associated high and low connection attachments;

[0026]FIG. 3 is an elevation view showing a variant of the precedingstrut, as seen looking forwards;

[0027]FIG. 4 is a plan view of the FIG. 3 strut fitted with itsconnection structure, showing more clearly the top panel of saidstructure and how it is connected to the common axis structure;

[0028]FIG. 5 is an elevation view analogous to that of FIG. 2, with twocutaway portions showing sliding bearing surfaces for the telescopic rodwhich is in its pushed-in position that corresponds to supporting theaircraft on the ground;

[0029]FIG. 6 is a fragmentary view of the connection structure in whichthe common axis structure is integral with the top panel;

[0030]FIG. 7 is a perspective view showing another variant of the highattachment which is constituted by a totally rigid connection;

[0031]FIG. 8 shows yet another variant of the high attachment which isconstituted by a hinged connection;

[0032]FIG. 9 shows, by way of example, various embodiments of the lowattachment which is constituted by a hinged connection a) and b) or by aswivel connection c);

[0033]FIG. 10 is an elevation view showing yet another variant of theconnection structure associated with the strut, in which the common axisstructure is constituted by a separate part having lugs for connectionto the top and bottom panels;

[0034]FIG. 11 is a section view on XI-XI of FIG. 10 showing more clearlyhow the bottom attachment is arranged;

[0035]FIG. 12 is a perspective view seen from beneath showing anothervariant in which the common axis structure includes a panel portionfixed to the bottom panel; and

[0036]FIGS. 13 and 14 are diagrammatic plan views for explaining thebehavior of the landing gear of the invention while turning, and inparticular the self-steering effect obtained by the connection structureof the invention.

[0037]FIG. 1 shows an aircraft undercarriage 10 comprising a leg 11constituted by a cylindrical strut 12 of axis Z in which there slides atelescopic rod 13 constituting a shock absorber. At the free end of thetelescopic rod 13 there is hinged a rocker beam 14 carrying a multipleaxle wheel set, in this case having three axles 25 each carrying a pairof wheels R. There can also be seen the two arms 15, 16 of a torsionlink connecting the strut 12 to the beam 14, said arms 15, 16 beingconnected to associated lugs 17, 18.

[0038] The undercarriage 10 is shown in the landing gear-down position,i.e. the position in which the axis Z is substantially vertical. Thestrut 12 is also hinged to an aircraft structure (not shown), beingcapable of being pivoted by an associated connection structure about asubstantially horizontal axis referenced X which is highly offset fromthe sliding axis Z of the telescopic rod 13. In the gear-down position,the landing gear 10 is prevented from pivoting about the axis X in thelanding position by a brace 20, the bottom end of which is shown in thefigures, which brace is hinged to a top lug 19 of the strut 12. Itshould be observed that in this arrangement, the brace 20 works incompression only.

[0039] The essential characteristic of the landing gear 10 of theinvention lies in the particular arrangement of the connection structurereferenced 100 that connects the pivot axis X to the cylinder of the legstrut 12. In accordance with this characteristic, the connectionstructure 100 is essentially constituted by two panels 101 and 102connected to the strut 12 via two axially separate points 105 and 106.In the gear-down position as shown in FIG. 1, the panels 101 and 102(symbolized by shaded triangles) are located one above the other. Thereare thus both a top panel referenced 101 which is connected to the strut12 via a high attachment 105, and a bottom panel 102 connected to thestrut 12 via a low attachment 106. The two panels 101 and 102 connectthe two points 105 and 106, i.e. the associated attachments, to a commonaxis structure 103 which extends along the pivot axis X of the strut 12.The hinge bearings arranged at the ends of the common axis structure 103are referenced 104.

[0040] In accordance with an essential aspect of the invention, the highattachment 105 is rigid in twisting, whereas the low attachment 106 istolerant of twisting, thus allowing the strut 12 to warp somewhat whilethe aircraft is turning on the ground. This freedom of the strut 12 towarp relative to the low attachment 106 serves to optimize the strengthand the deformation behavior of the landing gear under the loads thatare generated by the aircraft taxiing. The twisting generated by thewheels R slipping while the aircraft is turning during taxiing istransmitted to the bottom of the strut 12 by the arms 15, 16 of thetorsion link. The strut 12 is highly resistant to twisting about itsaxis Z and it transmits any such twisting moment to its top end, wheresaid twisting moment is transmitted into the top panel 101 in the formof a bending moment which, ideally, loads this panel in its own plane.Because the low attachment 106 of the strut 12 tolerates twisting, thestrut has a certain amount of freedom to deform relative to the lowattachment, with the twisting moment warping the strut about saidattachment. This ensures that the specific loads generated while theaircraft is taxiing are taken up optimally, with the structure of thelanding gear being fully optimized from the points of view of strengthand deformation behavior.

[0041] Moments are generated about the pivot axis X both by the fractionof the aircraft weight supported by the landing gear 10 multiplied bythe offset of the strut from said pivot axis X and sometimes also by theground-parallel resultant of the aircraft braking force multiplied bythe height of the pivot axis above the ground. This total moment iscountered by the brace 20 which works continuously in compression, andthat turns out to be optimal for its stability and its resistance tofatigue.

[0042] It is advantageous to provide for the top panel 101 and thebottom panel 102 to extend in respective planes that contain the pivotaxis X of the strut 12, the plane of the top panel 101 beingsubstantially orthogonal to the sliding axis Z of the telescopic rod 13.FIG. 1 shows one such advantageous arrangement. In general, the top andbottom panels 101 and 102 are preferably constituted by plane parts withstiffening in their margins.

[0043] Various embodiments of the connection structure 100 are describedbelow with reference to FIGS. 2 to 12, and in particular embodiments ofthe high and low attachments 105 and 106 for connection to the strut 12.

[0044]FIG. 2 shows the strut 12 without its telescopic rod, fitted withits connection structure 100 constituted by the top panel 101, thebottom panel 102, and the common axis structure 103. The high attachmentof the top panel 101 to the strut 12 is constituted by a restrainedconnection 105.1 constituted by two pairs of superposed lugs 107. Thelow attachment 106 of the panel 102 to the strut 12 is constituted by ahinged connection 106.1 about an axis which is contained in the plane ofsaid panel and which extends parallel to the pivot axis X of the strut.This hinged connection is implemented by a spool 111 secured to thebottom end of the strut 12 held in a clevis at the bottom end of thepanel 102. At the top portion of the panel 102, the connection with thecommon axis structure 103 is a hinge connection coaxial about the axisX, while the connection between the common structure and the top panel101 is made via a lug 109 of said common structure.

[0045] The distance between the axes X and Z is referenced D, whichdistance corresponds to the large offset between these axes,which-is-characteristic of landing gear for aircraft of very largedimensions. Reference d indicates the large offset between the bottomconnection 106.1 and the axis Z, which distance d is selected to be assmall as possible.

[0046]FIG. 3 shows a variant that is similar to that shown in FIG. 2,the difference lying in the way in which the high connection 105.1between the top panel 101 and the strut 12 is fixed: there can be seenan assembly via two single lugs 107′ of the strut 12 each held in arespective clevis associated with the panel 101. This embodiment can beseen more clearly in the plan view of FIG. 4 which shows the structureof the top panel 101 with its connection at 108 to the two side lugs107′ and its connection at 110 with the lugs 109 secured to the commonaxis structure 103. The assembly is arranged symmetrically about theplane P with respect to transmitting twist, which plane P is themidplane containing the sliding axis Z of the telescopic rod, and theconnection fingers 108 work in shear, which is a very favorableconfiguration referred to as “dual shear”.

[0047]FIG. 5 corresponds to FIG. 2 and has two cutaway portions in thestrut 12 for showing top and bottom sliding bearing surfaces 21 and 22for engaging the telescopic rod 13 in the strut 12. FIG. 5 shows thetelescopic rod 13 in its pushed-in position, as occurs when the landinggear is supporting the aircraft on the ground: it can be seen that thehigh and low attachments 105 and 106 are provided at the same levels asthe sliding bearing surfaces 21 and 22 in this pushed-in position. Thus,loads normal to the axis Z generated while the aircraft is taxiing andpassing through these bearing surfaces 21 and 22 are countered directlyby the panels 101 and 102 of the connection structure 100, thus ensuringthat the strut 12 does not bend. The loads carried by the bearingsurfaces for the sliding rods 13 can then be resolved as loads lying inthe planes of the top and bottom panels 101 and 102, and the panels aresuitable for transmitting these loads to the aircraft effectively viahinge pins. The strut 12 is thus not subjected to any bending by thestresses that result from forces generated when the aircraft turns whiletaxiing because of the arrangement of the high and low attachments levelwith the bearing surfaces for the telescopic rod 13. The large offset dof the low attachment 106 for the bottom panel 102 at the bottom end ofthe strut has the effect, under a lateral turning force, of generating amoment tending to twist the strut about said attachment. Since the struthas a certain amount of freedom to deform relative to said lowattachment, the twisting moment warps the strut about said lowattachment. This warping displacement is communicated to the rocker beamof the landing gear by the torsion link arms, thereby causing the beamto pivot in a direction which tends towards bringing closer theinstantaneous turning center of the aircraft, thus improving its abilityto turn: this produces a self-steering effect which is highlyadvantageous, and which is described in greater detail below withreference to FIGS. 13 and 14.

[0048] In the variants descried above, the common axis structure 103 isa separate part including the pivot bearings 104 enabling the strut 12to pivot about the axis X, said separate part being fixed to the top andbottom panels 101 and 102 via lugs that are secured to the part or tosaid panels. FIG. 6 shows a variant in which the common axis structure103 is integral with one of the panels of the connection structure 100,and specifically the top panel 101.

[0049]FIG. 7 shows another variant for the high attachment 105 betweenthe top panel 101 and the strut 12. This high attachment is constitutedby a totally rigid connection 105.2 which can be made by welding to thestrut 12, or which can be integral with said strut by being implementedas a single piece.

[0050] In FIG. 8, the high attachment between the top panel 101 and thestrut 12 is constituted by a connection 105.3 that is hinged about anaxis containing in the plane of said top panel 101 and extendingparallel to the pivot axis X of said strut. The top panel 101 isterminated by a clevis 122 holding a projection or spool 121 secured tothe strut 12, to which said panel is hinged.

[0051]FIG. 9 shows various possible embodiments for the low attachment106 connecting the bottom panel 102 of the connection structure 100 tothe strut 12.

[0052] In a), the low attachment of the bottom panel 102 to the strut 12is constituted by a connection 106.1 hinged about an axis contained insaid panel and extending parallel to the pivot axis X of the strut. Thisis a hinged connection about a clevis 112 at the bottom end of thebottom panel 102, which clevis is hinged onto a spool 111 secured to thestrut 12. In b), the hinged connection 106.2 is constituted by a clevisconstituted by two lugs 113 associated with the strut 12 holding asingle portion 114 at the bottom end of the bottom panel 102. In c) thelow attachment between the bottom panel 102 and the strut 12 isconstituted by a swivel connection 106.3 comprising a ball 116 receivedin a socket at the bottom end of the bottom panel 102 and mounted on astub axle 115 projecting from the strut 12.

[0053]FIG. 10 shows another variant in which the common axis structure103 is a separate part presenting lugs 109 and 117 for connection to thetop and bottom panels 101 and 102. The high attachment 105.1 correspondsto the attachment described above with reference to FIGS. 2 and 3. Thelow attachment between the bottom panel 102 and the strut 12 isconstituted by a restrained connection 106.4 with at least oneprojecting lug 118, in this case two such lugs, that are secured to thestrut 12, the fixing pins being referenced 119. The vicinity of the lowattachment 106.4 is also shown in section in FIG. 11 which enables itsstructure to be understood more clearly. The lugs 118 are lightweight soas to ensure that the bottom attachment tolerates twisting.

[0054]FIG. 12 shows that the common axis structure 103 includes a paneltorsion 120 fixed to the bottom panel 102, said panel portion beingcoplanar with and extending the bottom panel 102. The low attachment106.1 is hinged to lugs 111′ projecting from the strut 12.

[0055]FIGS. 13 and 14 are plan views for showing how the aircraftlanding gear of the invention behaves when the aircraft turns whiletaxiing, the instantaneous turning center being the point referenced C.

[0056] While turning, the resultant of the forces generated via therespective wheels R due to their slip due to the fact that their meanplane is not parallel to the tangent to the track they are followingwhile the aircraft is turning about the instantaneous center of rotationC (said plane making an angle referenced a with the tangent to thetrack, as shown for the rear right-hand wheel of the landing gear), canbe represented overall by a lateral force referenced L applied to theaxis Z of the strut and the associated sliding rod, and the lowattachment of the bottom panel of the connection structure 100 has theeffect that the lateral force creates a warping moment of value M=h.L.This moment causes the strut to deform in twisting through an angle b asshown in FIG. 14. The strut 12 then causes the rocker beam 14 to turntogether therewith by means of the torsion link so that the beam turnsin such a manner as to reduce the slip angles a, thereby reducing tirewear, and also reducing the forces to which the structure of the landinggear is subjected. This makes the instantaneous turning center C comenearer, thereby reducing the turning circle and consequently improvingthe turning ability of the aircraft. The angle a becomes an angle a′where a′=a−b. FIG. 13 shows the situation that would apply if thelanding gear were perfectly rigid in twisting, with the angle a thenremaining constant throughout the turning track. In contrast, FIG. 14shows the behavior that results from the tolerance to twisting of thelow attachment, with warping of the strut giving rise to turning throughan angle b, thus providing landing gear that is capable of deformingunder turning forces, and that is suitable for taking advantage of theabove-mentioned self-steering effect.

[0057] The invention is not limited to the embodiments described above,but on the contrary covers any variant using equivalent means toreproduce the essential characteristics specified above.

1/ Aircraft landing gear of the type comprising a leg (11) constitutedby a strut (12) in which a telescopic shock-absorber rod (13) slidesalong a sliding axis (Z), the free end of the rod being hinged to arocker beam (14) carrying a wheel set having multiple axles, said strutbeing hinged to a structure of the aircraft and being capable of beingpivoted by an associated connection structure about a substantiallyhorizontal axis (X) that is highly offset from the sliding axis (Z) ofthe telescopic rod (13) which is vertical in the gear-down position, thelanding gear being characterized in that the connection structure (100)is essentially constituted by two panels (101, 102) connecting twoaxially separated points of the strut (12) to a common axis structure(103) extending along the pivot axis (X) of said strut, in such a mannerthat in the gear-down position said panels are disposed one above theother, with a top panel (101) which is connected to the strut (12) via ahigh attachment (105) which is rigid in twisting, and with a bottompanel (102) which is connected to the strut (12) via a low attachment(106) which tolerates twisting, thereby allowing the strut (12) to warpto some extent when the aircraft is turning while taxiing. 2/ Landinggear according to claim 1, characterized in that the top panel (101) andthe bottom panel (102) both extend in respective planes each containingthe pivot axis (X) of the strut (12), the plane of the top panel (101)being substantially orthogonal to the sliding axis (Z) of the telescopicrod (13). 3/ Landing gear according to claim 1 or claim 2, characterizedin that the top and bottom panels (101, 102) are constituted by planepieces with stiffened margins. 4/ Landing gear according to any one ofclaims 1 to 3, characterized in that the high attachment (105) betweenthe top panel (101) and the strut (12) is constituted by a fixedconnection (105.1). 5/ Landing gear according to any one of claims 1 to3, characterized in that the high attachment (105) between the top panel(101) and the strut (12) is constituted by a totally rigid connection(105.2) achieved by welding to or by being formed integrally with saidstrut. 6/ Landing gear according to any one of claims 1 to 3,characterized in that the high attachment (105) between the top panel(101) and the strut (12) is constituted by a connection (105.3) that ishinged about an axis contained in the plane of said panel and extendingparallel to the pivot axis (x) of said strut. 7/ Landing gear accordingto any one of claims 1 to 6, characterized in that the low attachment(106) between the bottom panel (102) and the strut (12) is constitutedby a connection (106.1, 106.2) that is hinged about an axis contained inthe plane of said panel and extending parallel to the pivot axis (X) ofsaid strut. 8/ Landing gear according to any one of claims 1 to 6,characterized in that the low attachment (106) between the bottom panel(102) and the strut (12) is constituted by a swivel connection (106.3)associated with a stub axle (115) projecting from said strut. 9/ Landinggear according to any one of claims 1 to 6, characterized in that thelow attachment (106) between the bottom panel (102) and the strut (12)is constituted by a restrained connection (106.4) to at least one lug(118) projecting from said strut. 10/ Landing gear according to any oneof claims 1 to 9, characterized in that the high and low attachments(105, 106) are provided level with sliding bearing surfaces (21, 22) forthe telescopic rod (13) in the strut (12) when the rod is in itspushed-in position corresponding to supporting the aircraft on theground. 11/ Landing gear according to any one of claims 1 to 10,characterized in that the common axis structure (103) is a separate partincluding the pivot bearings (104) enabling the strut (12) to pivotabout its pivot axis (X), said separate part being fixed to the top andbottom panels (101, 102) via lugs that are secured thereto and/or tosaid panels. 12/ Landing gear according to any one of claims 1 to 10,characterized in that the common axis structure (103) is integral withone of the panels (101). 13/ Landing gear according to any one of claims1 to 10, characterized in that the common axis structure (103) includesa panel portion (120) that is fixed to the top panel (101) and/or to thebottom panel (102), said panel portion being coplanar with and extendingthe associated panel.